Investigating the Role of Wind Turbine Pitch using CFD

Abstract

Horizontal axis wind turbines are an attractive renewable energy source due to their very low carbon emission during their life cycle. In this study the effect of pitching the rotor blades of the NREL Phase VI rotor has been investigated in detail using CFD in order to allow a detailed torque analysis. Initial investigations have shown that at low rotational speeds the inboard section of the blade is responsible for the majority of the power generation. As the rotational speed increases the power producing section is shifted towards the blade tip. These trends are less pronounced when the blade is pitched which allows the blade to generate significantly more power at low rotational speeds. The improved low speed performance however comes at the cost of a significantly lower maximum power output. These findings are particularly relevant for turbines operating in unfavourable wind environments and for small scale turbines which solely rely on their aerodynamic torque for starting.